org.apache.bsf

Class BSFManager

public class BSFManager extends Object

This class is the entry point to the bean scripting framework. An application wishing to integrate scripting to a Java app would place an instance of a BSFManager in their code and use its services to register the beans they want to make available for scripting, load scripting engines, and run scripts.

BSFManager serves as the registry of available scripting engines as well. Loading and unloading of scripting engines is supported as well. Each BSFManager loads one engine per language. Several BSFManagers can be created per JVM.

Author: Sanjiva Weerawarana Matthew J. Duftler Sam Ruby Olivier Gruber (added original debugging support) Don Schwarz (added support for registering languages dynamically)

Field Summary
protected ClassLoaderclassLoader
protected StringclassPath
protected VectordeclaredBeans
protected static Hashtableextn2Lang
protected HashtableloadedEngines
protected ObjectRegistryobjectRegistry
protected PropertyChangeSupportpcs
protected static HashtableregisteredEngines
protected StringtempDir
protected static Stringversion
Constructor Summary
BSFManager()
Method Summary
Objectapply(String lang, String source, int lineNo, int columnNo, Object funcBody, Vector paramNames, Vector arguments)
Apply the given anonymous function of the given language to the given parameters and return the resulting value.
voidcompileApply(String lang, String source, int lineNo, int columnNo, Object funcBody, Vector paramNames, Vector arguments, CodeBuffer cb)
Compile the application of the given anonymous function of the given language to the given parameters into the given CodeBuffer.
voidcompileExpr(String lang, String source, int lineNo, int columnNo, Object expr, CodeBuffer cb)
Compile the given expression of the given language into the given CodeBuffer.
voidcompileScript(String lang, String source, int lineNo, int columnNo, Object script, CodeBuffer cb)
Compile the given script of the given language into the given CodeBuffer.
voiddeclareBean(String beanName, Object bean, Class type)
Declare a bean.
Objecteval(String lang, String source, int lineNo, int columnNo, Object expr)
Evaluate the given expression of the given language and return the resulting value.
voidexec(String lang, String source, int lineNo, int columnNo, Object script)
Execute the given script of the given language.
ClassLoadergetClassLoader()
Get classLoader
StringgetClassPath()
Get classPath
static StringgetLangFromFilename(String fileName)
Determine the language of a script file by looking at the file extension.
ObjectRegistrygetObjectRegistry()
Return the current object registry of the manager.
StringgetTempDir()
Get tempDir
static StringgetVersion()
Returns the version string of BSF.
voidiexec(String lang, String source, int lineNo, int columnNo, Object script)
Execute the given script of the given language, attempting to emulate an interactive session w/ the language.
static booleanisLanguageRegistered(String lang)
Determine whether a language is registered.
BSFEngineloadScriptingEngine(String lang)
Load a scripting engine based on the lang string identifying it.
ObjectlookupBean(String beanName)
return a handle to a bean registered in the bean registry by the application or a scripting engine.
voidregisterBean(String beanName, Object bean)
Registering a bean allows a scripting engine or the application to access that bean by name and to manipulate it.
static voidregisterScriptingEngine(String lang, String engineClassName, String[] extensions)
Register a scripting engine in the static registry of the BSFManager.
voidsetClassLoader(ClassLoader classLoader)
Set the class loader for those that need to use it.
voidsetClassPath(String classPath)
Set the classpath for those that need to use it.
voidsetObjectRegistry(ObjectRegistry objectRegistry)
Set the object registry used by this manager.
voidsetTempDir(String tempDir)
Temporary directory to put stuff into (for those who need to).
voidterminate()
Gracefully terminate all engines
voidundeclareBean(String beanName)
Undeclare a previously declared bean.
voidunregisterBean(String beanName)
Unregister a previously registered bean.

Field Detail

classLoader

protected ClassLoader classLoader

classPath

protected String classPath

declaredBeans

protected Vector declaredBeans

extn2Lang

protected static Hashtable extn2Lang

loadedEngines

protected Hashtable loadedEngines

objectRegistry

protected ObjectRegistry objectRegistry

pcs

protected PropertyChangeSupport pcs

registeredEngines

protected static Hashtable registeredEngines

tempDir

protected String tempDir

version

protected static String version

Constructor Detail

BSFManager

public BSFManager()

Method Detail

apply

public Object apply(String lang, String source, int lineNo, int columnNo, Object funcBody, Vector paramNames, Vector arguments)
Apply the given anonymous function of the given language to the given parameters and return the resulting value.

Parameters: lang language identifier source (context info) the source of this expression (e.g., filename) lineNo (context info) the line number in source for expr columnNo (context info) the column number in source for expr funcBody the multi-line, value returning script to evaluate paramNames the names of the parameters above assumes arguments values of the above parameters

Throws: BSFException if anything goes wrong while running the script

compileApply

public void compileApply(String lang, String source, int lineNo, int columnNo, Object funcBody, Vector paramNames, Vector arguments, CodeBuffer cb)
Compile the application of the given anonymous function of the given language to the given parameters into the given CodeBuffer.

Parameters: lang language identifier source (context info) the source of this expression (e.g., filename) lineNo (context info) the line number in source for expr columnNo (context info) the column number in source for expr funcBody the multi-line, value returning script to evaluate paramNames the names of the parameters above assumes arguments values of the above parameters cb code buffer to compile into

Throws: BSFException if anything goes wrong while running the script

compileExpr

public void compileExpr(String lang, String source, int lineNo, int columnNo, Object expr, CodeBuffer cb)
Compile the given expression of the given language into the given CodeBuffer.

Parameters: lang language identifier source (context info) the source of this expression (e.g., filename) lineNo (context info) the line number in source for expr columnNo (context info) the column number in source for expr expr the expression to compile cb code buffer to compile into

Throws: BSFException if any error while compiling the expression

compileScript

public void compileScript(String lang, String source, int lineNo, int columnNo, Object script, CodeBuffer cb)
Compile the given script of the given language into the given CodeBuffer.

Parameters: lang language identifier source (context info) the source of this script (e.g., filename) lineNo (context info) the line number in source for script columnNo (context info) the column number in source for script script the script to compile cb code buffer to compile into

Throws: BSFException if any error while compiling the script

declareBean

public void declareBean(String beanName, Object bean, Class type)
Declare a bean. The difference between declaring and registering is that engines are spsed to make declared beans "pre-available" in the scripts as far as possible. That is, if a script author needs a registered bean, he needs to look it up in some way. However if he needs a declared bean, the language has the responsibility to make those beans avaialable "automatically."

When a bean is declared it is automatically registered as well so that any declared bean can be gotton to by looking it up as well.

If any of the languages that are already running in this manager says they don't like this (by throwing an exception) then this method will simply quit with that exception. That is, any engines that come after than in the engine enumeration will not even be told about this new bean.

So, in general its best to declare beans before the manager has been asked to load any engines because then the user can be informed when an engine rejects it. Also, its much more likely that an engine can declare a bean at start time than it can at any time.

Parameters: beanName name to declare bean as bean the bean that's being declared type the type to represent the bean as

Throws: BSFException if any of the languages that are already running decides to throw an exception when asked to declare this bean.

eval

public Object eval(String lang, String source, int lineNo, int columnNo, Object expr)
Evaluate the given expression of the given language and return the resulting value.

Parameters: lang language identifier source (context info) the source of this expression (e.g., filename) lineNo (context info) the line number in source for expr columnNo (context info) the column number in source for expr expr the expression to evaluate

Throws: BSFException if anything goes wrong while running the script

exec

public void exec(String lang, String source, int lineNo, int columnNo, Object script)
Execute the given script of the given language.

Parameters: lang language identifier source (context info) the source of this expression (e.g., filename) lineNo (context info) the line number in source for expr columnNo (context info) the column number in source for expr script the script to execute

Throws: BSFException if anything goes wrong while running the script

getClassLoader

public ClassLoader getClassLoader()
Get classLoader

getClassPath

public String getClassPath()
Get classPath

getLangFromFilename

public static String getLangFromFilename(String fileName)
Determine the language of a script file by looking at the file extension.

Parameters: fileName the name of the file

Returns: the scripting language the file is in if the file extension is known to me (must have been registered via registerScriptingEngine).

Throws: BSFException if file's extension is unknown.

getObjectRegistry

public ObjectRegistry getObjectRegistry()
Return the current object registry of the manager.

Returns: the current registry.

getTempDir

public String getTempDir()
Get tempDir

getVersion

public static String getVersion()
Returns the version string of BSF.

Returns: version string in the form "abc.yyyymmdd" where "abc" represents a dewey decimal number (three levels, each between 0 and 9), and "yyyy" a four digit year, "mm" a two digit month, "dd" a two digit day.
Example: "240.20061006" stands for: BSF version 2.4.0 as of 2006-10-06.

Since: 2006-01-17

iexec

public void iexec(String lang, String source, int lineNo, int columnNo, Object script)
Execute the given script of the given language, attempting to emulate an interactive session w/ the language.

Parameters: lang language identifier source (context info) the source of this expression (e.g., filename) lineNo (context info) the line number in source for expr columnNo (context info) the column number in source for expr script the script to execute

Throws: BSFException if anything goes wrong while running the script

isLanguageRegistered

public static boolean isLanguageRegistered(String lang)
Determine whether a language is registered.

Parameters: lang string identifying a language

Returns: true iff it is

loadScriptingEngine

public BSFEngine loadScriptingEngine(String lang)
Load a scripting engine based on the lang string identifying it.

Parameters: lang string identifying language

Throws: BSFException if the language is unknown (i.e., if it has not been registered) with a reason of REASON_UNKNOWN_LANGUAGE. If the language is known but if the interface can't be created for some reason, then the reason is set to REASON_OTHER_ERROR and the actual exception is passed on as well.

lookupBean

public Object lookupBean(String beanName)
return a handle to a bean registered in the bean registry by the application or a scripting engine. Returns null if bean is not found.

Parameters: beanName name of bean to look up

Returns: the bean if its found or null

registerBean

public void registerBean(String beanName, Object bean)
Registering a bean allows a scripting engine or the application to access that bean by name and to manipulate it.

Parameters: beanName name to register under bean the bean to register

registerScriptingEngine

public static void registerScriptingEngine(String lang, String engineClassName, String[] extensions)
Register a scripting engine in the static registry of the BSFManager.

Parameters: lang string identifying language engineClassName fully qualified name of the class interfacing the language to BSF. extensions array of file extensions that should be mapped to this language type. may be null.

setClassLoader

public void setClassLoader(ClassLoader classLoader)
Set the class loader for those that need to use it. Default is he who loaded me or null (i.e., its Class.forName).

Parameters: classLoader the class loader to use.

setClassPath

public void setClassPath(String classPath)
Set the classpath for those that need to use it. Default is the value of the java.class.path property.

Parameters: classPath the classpath to use

setObjectRegistry

public void setObjectRegistry(ObjectRegistry objectRegistry)
Set the object registry used by this manager. By default a new one is created when the manager is new'ed and this overwrites that one.

Parameters: objectRegistry the registry to use

setTempDir

public void setTempDir(String tempDir)
Temporary directory to put stuff into (for those who need to). Note that unless this directory is in the classpath or unless the classloader knows to look in here, any classes here will not be found! BSFManager provides a service method to load a class which uses either the classLoader provided by the class loader property or, if that fails, a class loader which knows to load from the tempdir to try to load the class. Default value of tempDir is "." (current working dir).

Parameters: tempDir the temporary directory

terminate

public void terminate()
Gracefully terminate all engines

undeclareBean

public void undeclareBean(String beanName)
Undeclare a previously declared bean. This removes the bean from the list of declared beans in the manager as well as asks every running engine to undeclared the bean. As with above, if any of the engines except when asked to undeclare, this method does not catch that exception. Quietly returns if the bean is unknown.

Parameters: beanName name of bean to undeclare

Throws: BSFException if any of the languages that are already running decides to throw an exception when asked to undeclare this bean.

unregisterBean

public void unregisterBean(String beanName)
Unregister a previously registered bean. Silent if name is not found.

Parameters: beanName name of bean to unregister